Tampons conventionally sold in the United States employ means for insertion of the tampon pledget into the user's vagina. These means generally are in two parts with the outer part being a tube with an inner diameter slightly greater than the outer diameter of the tampon pledget. The second part of a tampon inserter means is some time of plunger which operates in cooperation with the tube to expel the pledget. The tubes are generally made of paper products such as cardboard or thermoplastic. Further, thermoplastic tubes generally have an insertion end which forms a hemispherical profile around the leading edge of the tampon to protect it and maintain its integrity during insertion. Commercially available tampons utilizing cardboard tubes, however, generally do not have this type of closure, but rather the leading edge of the tampon extends beyond the tube end. Both thermoplastic and paper derived tubes can be made with a reduced diameter base which can be used for gripping or to better maintain the plunger used for expulsion, or for both purposes.
The ideal tampon tube should be inexpensive, simple to make, easily disposable, attractive and hygienic. Both molded plastic and paper inserter tubes have not been completely satisfactory in meeting these desirable attributes. Tubes which are molded from the thermoplastics are neither water dispersible or flushable. Furthermore, the relative cost of thermoplastic is substantially greater than tubes which are made from paper or paper products. In addition, thermoplastic molded tubes having a hemispherical shaped leading edge comprising individual arcuate shaped lobes are extremely difficult to mold without providing lobes having sharp edges or flashing, i.e., irregularly shaped burrs of plastic. Such tubes could provide problems when being withdrawn from the vagina. Paper tubes, on the other hand, also have problems. Commercially available cardboard tubes for tampons are generally spirally wound and open at the leading edge which may result in a fiber slough when the tampon is inserted. The only known paper tubes with shaped tips are spirally wound with the shaping of the tips being accomplished by crushing, deforming and pleating the formed tube, or alternatively, by cutting triangular shaped petals in a preformed tube. Both of these methods for forming a tube which covers the insertion edge of the pledget are complex and in the case of crushing, deforming and pleating, expulsion of the tampon is extremely difficult. If a paper based tampon tube having a plurality or arcuate lobes with a hemispherical profile is desired, and the tubes are cut from a flat tampon blank, spiral winding will produce "ghosting", i.e., an overlap of the individual lobe segments due to the spiral winding. Attempts to produce such a leading edge with a spirally wound tube, therefore, are best performed after the tube is formed which is substantially more difficult. As can be seen from the previous discussion, while a paper based tampon tube with a hemispherical leading edge to cover the tampon is highly desirable from the standpoint of material cost and disposability, the difficulties in forming such a tube have inhibited their practical application. The tampon tube of this invention buy employing convolute winding and a thermoplastic coating overcomes many of the difficulties associated with paper-based tampon tube manufacture.
An approach which is currently preferred is to employ a water soluble or water dispersible thermoplastic binder which would aid in disposal of the applicator. If such a composition was used as the only thermoplastic binder material the applicator can be rendered flushable in conventional toilet systems. Coatings of different thermoplastics for the same applicator are also contemplated within the scope of this invention, and specific combinations of thermoplastics may be utilized for specific properties, e.g. surface finish, flushability, etc.
Suitable water dispersible and water soluble thermoplastic coatings are: polyethylene oxide, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, and hydroxypropyl cellulose.
The concept of convolute winding is well known. Representative patent disclosing the concept is U.S. Pat. No. 2,518,075, issued to W. R. Schere. Further, the concept of using a thermoplastic as an adhesive to attach an added element, i.e., a finger griping ring is disclosed in U.S. Pat. No. 3,572,339 issued to Joseph A. Voss and Carl W. Johnson.